Purification of solid aromatic hydrocarbons



Patented Aug. 18, 1931 UNITED STATES PATENT OFFICE JOSEPH BENNETT HILL, or PHILADELPHIA,CPENNSYLVANIA, ASSIGNOR 1 THE BARRETT coMrAm n CORPORATION or NEW JERSEY IPUR-IIEICATION 0F SOLID AROMATIG HYDROGARBONS 'No Drawing.

My invention relates to the process of purifying solid aromatic hydrocarbons, such as naphthalene, fluorene, acenaphthene, phenanthrene, etc. In the isolation and refining (5 of such hydrocarbons as usually effected, the oil fraction containing the hydrocarbon is allowed to stand until the solid hydrocarbon hascrystallized out, the oil beingsubsequent- 1y drained away from the crystals, leaving a product commonly known as drained saltsl, These crystals still contain considerable adhering oil and other impurities, as is indicated by their depressed melting points, the drained salts of naphthalene, for ex- 18 ample, showing a melting point usually between C. and 7 2 (1., whereas the melting point of pure naphthalene is slightly over 0. In the subsequent purifications of the hydrocarbons from this form, the usual pro- -m cedure includes a removal of the bulk of adhering oil by centrifuging or other means and a washing of the molten or dlssolved hydrocarbon at a fairly low temperature with sulfuric acid, aluminum chlor1de or other agent which tends to polymerize or otherwise remove impurities, such as the unsaturated hydrocarbons. The product is usually finally distilled to give the refined hydrocarbon. Where sulfuric ac1d is used for washing in the above process, the spent acid-obtained is of so little value that it is usually discarded. This acid COIlSlSlZS of a weak sulfuric acid contaminated with tar, sulfonic acids, etc, so as to make it practlcally worthless for other purposes as such and diflicult to recoveras a satisfactory acid. Where aluminum chloride or other agent 1s used for washing, the spent wash 1s also worthless.

' I have foundthat the above process can be much shortened and simplified washing the crude hydrocarbon directly w1th sulfur c acid at such a temperature that the sulfuric acid is completely exhausted in sulfonating 145 the hydrocarbon. The hydrocarbon can remaining behind in the still is practically Application filed. March 29, 1921. Serial No. 456,706.

acid residue. vWhere fractional distillation 68 is necessary, I prefer to have a fractionating column connected to the reaction vessel and distill the hydrocarbon from the sulfonic acid through this column. In some cases, however, it may be desirable to distill off the 0 hydrocarbon first and subsequently re-distill it with fractionation. 5

. The crude to be subjected to my treatment may be either the drained salts or may be the product obtained by removing the bulk 7 of the oily impurities from this. material by centrifuging or other means. If the latter is used, are'fined hydrocarbon may be obtained, having a melting point much closer to the theoretical than is obtained by the .80 usual refining process.

' Without wishing tolimit myself to any specific details or to any specific solid hydrocarbon, the following may serve as anexample of one of the ways in which my process canbe' carried out.

1000 pounds of crude naphthalene are melted and brought to a temperature of 150 0., at which temperatureBOO pounds of sulfuric acid are, added and the mixture agitated until the reaction is complete. Vacuum is applied to the mixture and the unsulfonated naphthalene distilled off through a handling of the crude hydrocarbon to produce refined, and the simultaneous production of a high quality, valuable by-product, to wit, the crude sulfonic acid of the hydrocarbon, the value of which is enhanced by the fact that it is substantially free from sul furic acid.

I claim:

1. The process of refining crude hydrocarbons of the aromatic series, which hydrocarbons are solid at ordinary temperature, comprising the treatment of the crude hydrocarbons with sulfuric acid in a proportion less than the theoretical amountrequired to completely sulfonate the hydrocarbons, said treatment being continued until substantially all of the sulfuric acid is used up and'the subsequent distillation of the unsulfonated hydrocarbons from the sulfonie acids produced.

2. The process of refining crude hydrocarbons of the aromatic series, which hydrocarbons are solid at ordinary temperatures, comprising the treatment of the crude hydrocarbon with sulfuric acid at a temperature sufficiently high to sulfonate impurities and a portion only of the hydrocarbon, and to causesubstantially all of the sulfuric acid to react and a subsequent distillation of the unsulfonated hydrocarbon from the sulfonic acid residue.

l 3. The process of refining crude naphthalene, comprising the treatment of the crude naphthalene with sulfuric acid in an amount suiiicient to sulfonate the impurities and aportion only of the naphtha'lene, and at a temperature suificiently high to cause substantially all of the sulfuric acid to react and a subsequent distillation of the unsulfonated naphthalene from the sulfonic acid residue. 7 a

4. The process of refining crude hydrocarbons of the aromatic series, which hydrocarbons are solid at ordinary temperatures, comprising the steps of treating the crude hydrocarbons with sulfuric-acid at a temperature ofabout150 C. and'in amount sulficient to react with all of the impurities but insufficient to sulfonate all of the hydrocarbons,

continuing the reaction until substantially all of the sulfuric acid has combined with the hydrocarbons and impurities, and separating thehydrocarbons from the resulting sulfonic acids by distillation.

5. A process of refining crude hydrocarbons of the aromatic series, which hydrocarbons are solid at ordinary temperatures, comprising the treatment of the hydrocarbon with an amount of sulfuric acid suificient for reaction with impurities contained in the hydrocarbon but less in quantity than the theoretical amount required to completely sulfonate the hydrocarbon, continuing the reaction until. substantially all of the sulfuric acid'is chemically combined with the hydrofrom the reaction residue.

carbon and impurities and subsequently dis tilling the unsulfonated hydrocarbon from the sulfonic acids produced.

6. A process of refining naphthalene which comprises treating naphthalene with an amount of sulfuric acid suflicient for reaction with impurities contained in the naphthalene but less in quantity than the theoretical amount required to completely sulfonate the naphthalene, continuing the reaction until substantially all of the sulfuric acid is chemically combined with the naphthalene and impurities and subsequently distilling the naphthalene from the sulfonic acids produced.

7. A process of refining naphthalene which comprises treating naphthalene at a temperature of about 150 C. with an amount of sulfuric acid suflicient for reaction with impurities contained in the naphthalene but less in quantity than the theoretical amount required to completely sulfonate the naphthalene, continuing the. reaction until substantially all of the sulfuric acid is chemically combined with the naphthalene and impurities and subsequently distilling the naphthalene from the sulfonic acids produced. i

8, The process of refining crude hydrocarbons of the aromatic series, which hydrocarbons are solid at ordinary temperatures, comprising the treatment of the crude hydrocarbon with sulfuric acid in an amount suiticient'to sulfonate substantially allthe impurities and a portion only of the hydrocarbon and at a temperature sufficiently high and for a sufiicient length of time to cause substantially all of the sulfuric acid to react. 1 -9. The process of refining'crude naphthalene, comprising the treatment of the crude naphthalene with sulfuric acid in an amount suificient' to sulfonate substantially all the impurities and a portion only ofthe naphthaa temperature of approximately 150C. and

the subsequent distillation of the naphthalene 11. Theprocess of refining crude hydro 'carbons'of the aromatic series, which hydrocarbons are solid at ordinary temperature, comprising the treatment of the crude hydrocarbon with sulfuric acid in a proportion sulficient to sulfonate all of the'impurities but less thanthe theoretical amount to sulfonate all of thehydrocarbons, said treatment bein continued until substantially all of the S111- furic'acid is used up, and the subsequent distillation' of the unsulfonated hydrocarbon from the sulfonic acids produced underla pressure less than atmospheric pressure;'; 1

,- 12, The pro'cess of refining naphthalene which comprises treating naphthalene at a temperature of about C. with an amount of sulfuric acid suificient for reaction with impurities contained in the naphthalene but less in quantity than the theoretical amount required to completely sulfonate the naphthalene, continuing the reaction until sub stantially all of the sulfuric acid is chemically combined with the naphthalene and impurities and subsequently distilling the naphthalene from the sulfonic acids produced under a pressure less than atmospheric pressure.

In testimony whereof I afiix my signature.

JOSEPH BENNETT HILL. 

